The present invention relates generally to the field of communication systems more particularly to wireless communication systems.
As wireless communication systems become more common, the emphasis in wireless communications is to provide feature rich services in a mobile environment. Mobile-to-Mobile calling patterns involving multiple party conferencing are expected to increase exponentially as more subscribers are added to wireless services.
This produces a need for a network infrastructure that supports both the existing connectivity paths and those new connectivity paths required to support a substantially higher mobile-to-mobile multiple party conferencing traffic percentage. Presently, wireless network infrastructures have an inherent need to convert between radio frequency (RF) encoded speech of a mobile and the 64 kilobit per second (kb) pulse code modulation (PCM) based telephony infrastructure of existing switching equipment. The exact process occurs in the reverse direction requiring the conversion of 64 kb PCM into RF encoded speech-frames. This conversion occurs multiple times in a mobile-to-mobile call scenario. Thus, conversion delay is introduced into the end-to-end path and quantization noise is increased that is highly noticeable to the mobile users. Both are highly noticeable to the mobile users.
Additionally, with any conferencing situation it is inherent that the connection of at least two mobiles multiple conversions between 64 kb PCM and encoded speech are encountered. The 64 kb PCM is directed through the network infrastructure to a three or six port conferencing circuit which takes incoming sample streams, aggregates, averages, and generates outgoing sample streams. The mobile""s encoded speech is converted, sent to the conferencing circuits, sent back, and then reconverting into encoded speech. Thus, additional delay beyond what is encountered for sample conversion is introduced into the end-to-end path and this is highly noticeable to the mobile users.
Additionally, new hardware is required because the wireless infrastructure requires additional trunk resources to connect both ends of the mobile-to-mobile call. Thus, a need exists for network infrastructures that support existing connectivity paths and provide new connectivity paths to support a higher mobile-to-mobile traffic percentage.
In accordance with the present invention, the problem of multiply converting the RF modulated encoded speech-frames, received from the transmit unit, into an intermediate 64 kb PCM and then back to RF modulated encoded speech-frames for transmission multiple receive units in a conference call environment is overcome by using an interface conference circuit that is programmable and has a matrix component that allows similar encoded speech-frame streams to cross-connect and differently encoded speech-frame streams to be cross-converted without any intermediate steps.
An example system of the invention includes a transmit unit that transmits an input signal of an input modulation encoded speech-frame type, a number of receive units that each receive an output signal of an output modulation encoded speech-frame type and a direct interface system that directly interfaces the input signal to each of the output signals.
The direct interface system includes a transmit conference interface circuit that directly interfaces the input signal to a data path signal and a receive interface conference circuit that directly interfaces the data path signal to each of the output signals.
The transmit conference interface circuit includes both a plurality of input modulation encoded speech-frame types and a plurality of output modulation encoded speech-frame types. One of the input modulation encoded speech-frame types represents the encoded speech-frame type of input signal and one of the output modulation encoded speech-frame types represents the encoded speech-frame type of each of output signal. Additionally, the transmit conference interface circuit include an interface conference matrix that directly interfaces the encoded speech-frame type of the input signal to the encoded speech-frame type of each of the output signals.